Why Reboot Router: DNS Cache

February 10, 2018

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Why reboot my Router ?

How does flushing a DNS cache help resolve some issues, and while you’re at it what’s DNS? We hope when you are finished with this article you will feel comfortable with a few things. First off, we hope you feel you had DNS explained in some detail. Secondly, we hope you understand a little further why it is important to reboot your router. You would be very surprised with how a simple reboot of your router can fix many of the issues you are having.

DNS

First, a quick review of what DNS is.

DNS is an acronym for the Domain Name System.

As you probably already know, every device on a network is identified by an IP (Internet Protocol) address. However, you and I rarely know or care what the IP addresses are; we use names instead, like “google.com”. DNS is what maps from names to IP addresses. When your computer accesses a domain name for the first time, it performs what’s called a DNS request, which boils down to asking “Hey, what’s the IP address for ‘google.com’?” Your computer is querying a DNS server whose job it is to answer exactly those kinds of questions. “Found it: ‘google.com’ is ‘60.22.33.185’”.(just a fictitious address)

DNS Cache

Once your computer gets an answer, it’s allowed to remember it for a period of time. Typically, it’s a day or two, but it actually varies based on the specific domain. For as long as your computer remembers that “google.com” is “60.22.33.185”, it doesn’t have to ask anyone. Once the time expires, it’s required to ask again, just in case it’s changed. The memory of all the DNS lookups your computer has performed is called the ‘DNS cache’. Sometimes, for various reasons, the cache becomes corrupt or out of date, or, to use a technical term, “messed up”. The symptoms vary, but the most common is that you can’t get to some web sites in your browser. You can “Flush” the DNS cache via Windows Command Prompt, but rebooting your machine has the same effect. Your DNS cache is not preserved across a reboot.

Other DNS Caches

The IP address for the DNS server may well be the IP address of your router. Many routers perform the DNS function for local networks. If they need to, they make the DNS request from your ISP’s DNS servers on your behalf.

This allows two things:

Your router can look up machines on your local network that it already knows.
It knows about them since it was the device that assigned them their IP addresses in the first place.
And since machines on your local network are not known on the internet anyway, they would not show up in the internet’s DNS servers.

Your router can cache DNS lookups. That means if you have more than one machine going to the same site,
the first one might cause the router to have to look it up,
but the second machine’s request for the same domain would already be in the router’s cache;
the router wouldn’t need to do anything more than simply return the answer.

And yes, this is another reason why rebooting your router is a frequent diagnostic step: your router’s DNS cache can also become “messed up”. In fact, it happens more frequently than most people expect. And just like your PC, rebooting your router forces it to start over with an empty DNS cache.

DNS is critical

DNS is a critical component of how things are located on the internet. As a result, there are threats. Imagine what would happen if someone was able to change the DNS information in a cache, or on a server, maliciously. You might ask for “goggle.com” and get some other random IP address, that would direct your browser to a malicious web site.

Now after reading all of the above you may ask yourself what has this got to do with Kodi ? It's about Computers ? Yes it is but the same applies to Android Boxes, FireTV & Sticks. Your Router is the link to the Internet so preventing it from “messing up” and using Windows Command Prompt, just reboot your router, which is perhaps easier to remember.

In Conclusion

We hope this article has opened your eyes to the importance of rebooting your router. Our second goal was to help you understand a little more about DNS cache and how this can play a role in your internet usage. Should you have any questions at all please feel free to visit us on Ares Forum. Our admin team is always available to assist you with your learning and troubleshooting needs.